9:00 AM MST, Thursday, January 10, 2019
A weak but intensifying storm will move through the central Rockies on Friday bringing some snow. The snow is likely to be a little wetter than usual for January with a gradient ranging from very little in the plains of eastern Larimer and Weld County, to some moderate amounts (exceeding 6 inches) in the Palmer Divide and foothills.
The most likely accumulation
There is a lot of variability due to the timing of storm intensification and whether there might actually be a little rain at the start. The most likely accumulation is 4-8 inches for the foothills and Palmer Divide area, 2-4 inches for most of the Denver-Boulder metro, 0-2 inches in Longmont, Fort Collins, Cheyenne, and Colorado Springs. The timing is mainly during the day on Friday, possibly beginning by sunrise and continuing into the evening. This outcome has about a 60% chance of occurring.
The low end possibility
The GFS, a reliable U.S. based model, has been consistently showing that the storm won’t really get going until it’s east of Colorado and thus the snowfall should be rather minor. Amounts with this model should range from 3-6 inches in the foothills, mountains, and Palmer Divide regions, 1-2 inches in the Boulder-Denver area and little or nothing in Longmont, Fort Collins, Greeley, and Cheyenne. This outcome has about a 30% chance of occurring.
The high-end possibility
Some of the mesoscale models based on the WRF have been more likely to begin intensifying the storm as it moves east through the central Rockies and tapping some subtropical Pacific moisture as it intensifies. These solutions suggest a 6-10 inch snowfall in the Denver area south of I-70 and extending north along foothills to Broomfield and Boulder. The amounts trail off rapidly to just 1-3 inches for northeast Boulder County, Larimer, and Weld counties. The trend seems to be away from this so this outcome has about a 10% chance of occurring.
Dry weather with seasonable temperatures. The air may be somewhat stagnant, so some haze along the Front Range urban corridor is likely.